When transporting an electronic device, such as a projector, packed in a cardboard box or the like, it is necessary to prevent the electronic device from being damaged by external impact. Accordingly, for example, a package cushion member 1′ having an upper pad 10′ and a lower pad 20′ has hitherto been used, as shown in FIG. 7. That is, a first backing board 3, the lower pad 20′, a projector 50 serving as a packed object, the upper pad 10′, and a second backing board 4 are stacked in that order inside a cardboard box 2, and an accessory box 5 is put therein so as to fill the clearance in the cardboard box 2.
The upper pad 10′ and the lower pad 20′ are produced by pulp molding or other means, and a plurality of upper-pad hollow projections 15 and a plurality of lower-pad hollow projections 25 project therefrom so as to surround a storage space 21 for the projector 50. Therefore, the projector 50 is protected from vibration during transportation while it is surrounded by the upper-pad hollow projections 15 and the lower-pad hollow projections 25 between the upper pad 10′ and the lower pad 20′, as shown in FIG. 8. Although not shown in FIG. 7, recesses 22 of the lower pad 20′ function as cushioning portions which protect the bottom surface of the projector 50, as shown in FIG. 8.
However, the cardboard box 2 with the projector 50 packed therein is sometimes inadvertently dropped during transportation. In such a case, for example, great impacts directed toward the bottom surface or the side of the cardboard box 2 are applied to the projector 50 inside the cardboard box 2, as shown by arrows A and B, and the projector 50 is sometimes broken.
Accordingly, as shown in FIG. 8, a structure is possible in which a reinforcing pad 30′ having bottom-protecting hollow projections 31, which are in contact with the recesses 22 of the lower pad 20′, is placed under the lower pad 20′. In such a structure, since the recesses 22 of the lower pad 20′ and the bottom-protecting hollow projections 31 of the reinforcing pad 30′ absorb the impact applied in the direction of arrow A, the bottom surface of the projector 50 is protected.
When an impact in the direction of arrow B is applied to the projector 50, the base portions of the upper-pad hollow projections 15 and the base portions of the lower-pad hollow projections 25 are crushed to absorb the impact. In contrast, since leading end portions 150 (lower ends) of the upper-pad hollow projections 15 and leading end portions 250 (upper ends) of the lower-pad hollow projections 25 have high rigidity with respect to the force applied from the direction of arrow B, when an impact is applied again after the base portions of the upper-pad hollow projections 15 and the base portions of the lower-pad hollow projections 25 are crushed, the center portion in the thickness direction of the outer case of the projector 50 abuts the leading end portions 150 of the upper-pad hollow projections 15 and the leading end portions 250 of the lower-pad hollow projections 25, and receives a great force. Furthermore, while, of upper, middle, and lower cases 51, 52, and 53 which constitute the outer case of the projector, the upper case 51 and the lower case 53 are formed of a die-cast case or a thick resin case which is rigid, the middle case 52 is made of an aluminum plate. Consequently, the center portion in the thickness direction of the outer case is more prone to distortion than the upper and lower portions. For this reason, when the leading end portions 150 of the upper-pad hollow projections 15 and the leading end portions 250 of the lower-pad hollow projections 250 abut the middle case 52, which is easily distorted, the middle case 52 is substantially dented.
In view of the above problems, an object of the present invention is to provide a package cushion member which can reliably prevent an outer case of a packed object from being broken even when the outer case is easily distorted at the center portion in the thickness direction, and to provide a package using the package cushion member.